<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>01 回顾js</title>
  <style>
    *{
      margin: 0;
      padding: 0;
    }
    div{
      height: 200px;
      background: pink;
      margin-bottom: 10px;
      display: none;
    }

  </style>
</head>
<body>
<div></div>
<div></div>
<div></div>
<script></script>
</body>
</html>